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Are my amp tubes dying early, and if yes, what could I do?

Check AC line voltage. You can use a Variac to lower the line voltage to save tubes.
I set my 123 VAC line to 115 VAC.
I only get 100V from the wall anyway ;)
Yes. You can also tell if you just barely nudge the tube a bit. If it rustles or pops it's likely dirty.

Also avoid tube rolling. This just jacks up sockets and pins faster IMHO. Plus you can get pretty much the same effect just by doing 0.5 or 1db bass or treble shelves lol.

No, I'm not a tube or analog "purist", but I like the repairability of valve amps. I still have a st70 from 1962 with nothing replaced but the can cap. Original Dynaco output tubes too. This stuff can last virtually forever.

Hit me up if you need anything. Good luck.
I see. Well I think the tube is broken, since the popping travels to the other channel if I swap the left and right tubes. I received the replacements today and now the amp is fine again. I also realized that it was indeed the (second) original 3 year old tube that failed this time. It probably saw more than 4500 hours of use. Factor in something like 600 cycles and the hot climate in summer, maybe the tubes really wore out normally. If I have time, I'll have a look inside, but for now I'm happy that I can use the amp again ;).
 
Hello,

Almost 3 years ago, I bought an Elekit TU-8200R kit. I put it together as per the instructions (I'd say I have decent soldering skills) and it ran great.

After about 1 year, one channel started cracking and popping loudly, no matter the volume setting (scary!). I swapped the tubes on the left and right channels and identified that one of the 6L6GC (JJ) tubes might be defective, as the popping traveled with it. I obtained a replacement and alas, the problem was fixed.

However, now, after another 18 months or so, I again get loud popping on one channel. Unfortunately I did not note down which tube is the newer one to know whether it's the original second tube that failed, or the replacement, and whether it happened on the same channel. I ordered another one, and this time I'll make sure to mark which one is newer.

Anyway, this seems odd to me. I couldn't get a conclusive answer as to how long 6L6GC tubes usually last. Some say 2500 to 5000 hours. Others say it depends on how hard you drive them. Others say incorrect biasing affects endurance (but I don't think the TU-8200R could be adjusted). Yet others say that they've used the same tubes for decades on their (guitar) amps.

My amp is connected to a pair of Yamaha NS1000M speakers, source is a Shiit Modi+ DAC, I set the volume to about 50%, and I just listen to music about 150 days a year. Sometimes the amp runs all day. Yes, sometimes I forget to turn it off over night, so the tubes might experience the occasional 30h event. So a very generous estimate would be around 150*15 = 2250 hours per year, which is in line with some of the sources I found.

Well, if this is indeed as expected, I'm kinda surprised this isn't highlighted more prominently in the solid state vs. tube debate. To me, the amp sounds like any other amp. Sounds great. My main reason for buying it was to just try a tube amp and because I like assembling stuff. But I have some solid state amps from the 80s where the only problem is the occasional corroded control knob, and I've been using them just as much. They, too, sound great. I mean, I can afford it, but spending 30 bucks on a new tube every year seems weird.

If it's not expected, what could I possibly do? It works and sounds just fine most of the time. Kinda doubt there's something wrong on the inside, but I'm no expert.

Any opinions?

Thank you!

PS: This is the assembly guide with schematics and all
The first thing to check is the bias voltage on the control grids of the output tubes. A clue that it isn't negative enough would be the plates in those tubes have a dull reddish glow.
 
I'm curious, what brand of tubes are you using and where are you getting them?
I've run a home built 6L6GC amp at higher current than recommended and didn't have any failures when I was using it regularly. I typically used tubes from the late 50's and early 60's though.
 
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The first thing to check is the bias voltage on the control grids of the output tubes. A clue that it isn't negative enough would be the plates in those tubes have a dull reddish glow.
Definitely a good quick 'n' dirty diagnostic. I will note that other things can cause redplating -- e.g., bad coupling capacitors, or even poor contact in a tube socket -- which might be an issue with only one or a couple of specific pins. The latter's a potential issue that was sort of brought up earlier in the context of 'popping'.

Redplating in most AF power amplifiers is a very bad thing.

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Danger! Danger! Warning, Will Robinson!

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N.B. A nice cherry glow on the plates is sometimes A-OK in RF power amplifiers (transmitters), so there is that. ;)
 
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